Marine decapod crustaceans have a very low reported natural incidence of neoplasia, even though it has been shown that crabs and lobsters contain relatively high concentrations of procarcinogens such as polycyclic aromatic hydrocarbons when harvested from polluted waters. Reasons for this apparent resistance to neoplasia will be investigated, with the spiny lobster as model. Processes to be investigated are those involved in the initiation of carcinogenesis, namely biotransformation of procarcinogens to ultimate carcinogens, and binding of ultimate carcinogens to DNA and other cellular macromolecules. Related investigations will determine the potential for transfer of procarcinogens or their reactive metabolites (proximate carcinogens) from crustacea to fish. In vitro and in vivo studies in spiny lobster will investigate factors modulating procarcinogen bioactivation, detoxication and excretion as well as the binding of ultimate carcinogens to DNA and other macromolecules. The techniques used will mainly be established biochemical and physiologicaL methods and will employ radiolabelled procarcinogens to ensure adequate sensitivity. Results of these studies will be of importance in three areas: firstly, in understanding the biological basis for resistance to chemical carcinogenesis exhibited by the spiny lobster and other crustaceans; secondly, in predicting whether animals which eat procarcinogen-exposed crustacea will absorb proximate carcinogens formed by the crustacean and therefore be at increased risk for developing neoplasms; thirdly, in providing basic information about factors influencing xenobiotic biotransformation in invertebrates.